Strand twisting arrangement for an open-ended yarn spinning system

ABSTRACT

A funnel-shaped strand twisting head in an open-ended yarn spinning system has a working region that includes circumferentially alternating roughened and smooth portions. The head is disposed between a pair of strand advancing rolls and a rotating spinning chamber from which the strands are payed out. During each revolution of the spinning chamber in a forward direction, the advancing strands alternately contact the rough and smooth portions of the head. As a result, a reverse twist is superimposed on the normally forward-twisted strands to strengthen the strands in the region between the head and the spinning chamber and to maintain the twist point in the chamber at a fixed location.

United States Patent [191 [11] 3,834,147 Havranek et al. Sept. 10, 1974 [54] STRAND TWISTING ARRANGEMENT FOR 3,543,500 12/1970 Bancroft et al. 57/58.89 AN PEN ENDED YARN SPINNING 3,739,565 6/1973 Nagel 57/58.89 SYSTEM 3,778,989 12/1973 Schon 57/58.89 3,789,597 2/1974 Schon 57/58.89 [75] Inventors: Zdenek Havranek; Miroslav Jiskra,

both of Usti nad Orlici; Miroslav Kubovy, Dolni Dobrouc; Josef Primary Exammer-Donald E. Watkins Stary, Usti nad Orlici; Vera Vierikova, Dlouha Trebova, all of Czechoslovakia [57] ABSTRACT [73] Asslgnee: g zg gzgggfig A funnel-shaped strand twisting head in an openended yarn spinning system has a working region that [22] Filed: Oct. 15, 1973 includes circumferentially alternating roughened and smooth portions. The head is disposed between a pair [21] Appl' 406633 of strand advancing rolls and a rotating spinning chamber from which the strands are payed out. Dur- [30] Foreign Application Priority Data ing each revolution of the spinning chamber in a for- Oct. 16, 1972 Czechoslovakia 6956-72 ward direction, the advancing t s ternately contact the rough and smooth portions of the head. As [52] US. Cl. 57/58.89, 57/156 a result, a reverse twist is superimposed on the [51] Int. Cl. D01h 7/00, DOlh 1/12 mally forward-twisted Strands to strengthen the [58] Field of Search 57/58.8958.95, 156 Strands in the region between the head and the spinning chamber and to maintain the twist point in the [5 Referen es Cit d chamber at a fixed location.

UNITED STATES PATENTS 3.457,716 7/1969 Storek 57/58.89 8 Drawmg 7 23 K 5 6 g E STRAND TWISTING ARRANGEMENT FOR AN OPEN-ENDED YARN SPINNING SYSTEM BACKGROUND OF THE INVENTION Open-ended yarn spinning systems conventionally include facilities for separating fibers and for collecting the separated fibers as strands on a surface of a rotary spinning chamber. The collected strands are advanced axially downstream out of the chamber and are taken up by a suitable device such as a bobbin.

During the advance, the moving strands are twisted into yarn in a forward direction (i.e., in a direction corresponding to the direction of rotation of the spinning chamber) by means of a twisting head carried by an elongated withdrawing member. The withdrawing member is disposed coaxial with the spinning chamber and located intermediate with the rollers and the collecting surface of the chamber. The head has a funnelshaped working region upon which the moving strands bear.

The distribution of the lightness of the twist (i,e. the pitch of the twist helix) between the rollers and the collecting surface is an important factor in the overall strength of the resulting yarn. In previous designs, the twisting head had a completely smooth working region, and the resulting twist was found to be tightest in the region adjacent the rollers and progressively looser in the direction toward the collecting surface of the spinning chamber. The relative looseness of the twist in the space between the working region of the head and the collecting surface resulted in severe weakening of the yarn, and a high breakage rate.

In an attempt to alleviate this problem, newer designs have equipped the head working region with separate roughened and smooth portions each of which is coax-, ial with the axis of advance and is disposed completely around the circumference of the working region. The roughened portion imparts a reverse twist (i.e., a twist in the direction opposite to the direction of rotation of the spinning chamber) to the strands to distribute the overall tightness of the twist more evenly and to thereby strengthen the yarn. A smooth portion of the working region is disposed upstream of the roughened region to clamp vibrations in the yarn caused by the reverse twist. Several problems have attended these new designs. For example, the positioning of the smooth portion of the working surface upstream of the roughened surface tends to inhibit the reverse twist from propagating to the collecting surface, thereby partially nullifying the desired strand strength enhancement. In addition, such arrangement of roughened and smooth portions causes the twist point of the collecting surface to move in a reverse direction as the chamber is rotated in a forward direction, thereby causing further weakening of the yarn. Finally, since the drag imparted to the yarn by the roughened surface is present at all angles of rotation of the chamber, difficulties may be encountered in the start-up of the rotating portions of the system.

SUMMARY OF THE INVENTION The arrangement of the present invention eliminates all the above-noted disadvantages by providing improved construction of the funnel-shaped working region in a twisting head of the type described above.

In'this improved construction, the roughened portion of the working region extends only partially around the circumference of the working region, and the smooth portion occupies the remaining portion of the working region. The roughened and smooth portions may be substantially flush or, if desired, the roughened region may project slightly in an upstream direction relative to the smooth portion.

The roughened portion may either be a single region or a plurality of discrete elements distributed in spaced relation around the periphery of the working region and separated by successive parts of the smooth portion.

In one feature of the invention, the roughened element is disposed in a circumferential groove cut into the working region. Advantageously, an edge of the element may project from the groove in an axially upstream direction to form a bearing point for the advancing strands.

With these improved arrangements, each revolution of the rotating spinning chamber about the axis of advance causes the advancing and rotating strands to alternately contact the rough and smooth portions of the working region. This action applies a pulsating, cyclically intermittent retardation to the rotating strands to form a stable, significant reverse twist at the collecting surface. As a result, the strand twist tightness distribution is corrected and the undesired movement of the twist point on the collecting surface is prevented. Moreover, because the roughened portion is disposed only partially around the circumference of the working region, the drag on the yarn during start-up of the spinning apparatus is greatly minimized.

BRIEF DESCRIPTION OF THE DRAWING The invention is further set forth in the following detailed description taken in conjunction with the appended drawing, in which:

FIG. 1 is a view, partially in section, of an openended yarn spinning system showing details of facilities for advancing and twisting strands into yarn;

FIG. 2 is an end view, taken on line 22 of FIG. 1, illustrating a partially roughened working region of a funnel-shaped twisting head in the arrangement of FIG.

FIGS. 3-8 are end views of alternative forms of the twisting head in accordance with the invention, illustrating different geometric shapes and configurations for the roughened portion thereof;

FIGS. 9-10 are longitudinal views in section illustrating various twisting heads each having a roughened portion that is flush with the remainder of the working region;

FIGS. 11 is a longitudinal view in section illustrating a twisting head having a roughened. portion that projects beyond the remainder of the working region;

FIGS. 12 and 13 are end and sectional longitudinal views, respectively, of a twisting head having a circumferential groove for receiving a discrete arcuate roughened element;

FIG. 14 is a longitudinal view in section of a twisting head similar to that of FIGS. 12 and 13 but including a roughened element having an edge extending from the groove; and

FIG. 15 is a longitudinal view in section of a twisting head similar to that of FIGS. 12 and 13 but having an additional roughened element disposed in the groove.

DETAILED DESCRIPTION Referring now to the drawing, a plurality of fibers 18 to be twisted into yarn are introduced via an air duct 20 into a subassembly 50 of an open-ended yarn spinning system. The duct 20 receives the fibers from a suitable fiber separating device (not shown) of the spinning system via rolls 19. The subassembly 50 includes a cylindrical housing2 having an axis 51. A spinning chamber 1 is disposed within and coaxial with the housing 2. The chamber 1 is mounted and is joumalled for rotation in a bearing 4 carried by the housing 2. The shaft 3 terminates in a pulley 5 outside the housing 2. The pulley is connected via a belt 6 to a suitable common drive (not shown) for the spinning system.

The spinning chamber 1 has a sloping wall 13 which terminates at a collecting surface 14. Vent ports 16 extend obliquely from an internal coaxial recess of the spinning chamber to an interior cavity 17 of the housing 2 as shown.

The housing 2 is provided with a lid 7 having a projecting portion 8. The portion 8 extends into the spinning chamber 1 and has a concave inner surface 11 spaced by an axial distance A from the collecting surface 14. (Preferably, the distance A should be as small as possible). The air duct extends obliquely through the lid 7 and exists at an aperture 9 in a side wall 52 of the projecting lid portion 8. The side wall 52 is disposed adjacent the sloping side wall 13 of the chamber 1.

With this arrangement, a partial vacuum established inside the chamber 1 by the vent ports 16 upon the rotations of the chamber in a forward direction (represented by an arrow 53 in FIG. 2) will propel the fibers 18 through the air duct 20 in the direction of an arrow 54 (FIG. 1) and out of the aperture 9 of the projecting portion 8 of the lid 7 to be collected on the collecting surface 14 of the chamber 1.

The collected fibers are payed out in the form of strands 21 from the collecting surface 14 in an axially downstream direction represented by an arrow 56 by the action of rolls 22.

An elongated hollow member 10 coaxial with the chamber 1 is carried in the concave surface 11 of the lid 7, and includes a funnel-shaped twisting head 12. The head 12 hasa constricted mouth 23 forming part of working region 24 (illustratively in the form of a surface of revolutions) for twisting the strands 21 as they are advanced axially from the collecting surface 13.

Rotation of the chamber 1 in the forward direction causes the strands 21 to rotate in continuous contact with the working region 24 of the twisting head. The resulting arrangement is shown in FIG. 1 at the time of contact of the strands 21 with the uppermost part of the working region 24. During such rotation the working region 24 normally serves to impart to such strands a forward twist (i.e., a twist in the direction of rotation in the chamber 1) to form yarn which after passing through the rolls 22 be collected by a suitable take-up device (not shown) such as a bobbin.

The forward twist imparted to the advancing strands 21 by the working region 24 normally exhibits a maximum tightness (i.e., a minimum pitch of twist helix) immediately adjacent the rolls 22, such twist becoming progressively looser in an axial direction from the rolls 22 toward the collecting surface 14. Since the resulting relatively loose twist exhibited in the region between the head 12 and the collecting surface 14 diminishes the strand strenght, it has been customary to roughen a circumferential strip of the working surface 24 for imparting a reverse twist (i.e., a twist in the direction opposite to that imparted by the direction of the chamber) to the portion of the strands upstream of the head 12.

In accordance with the invention, further strengthening of the strands is accomplished by disposing a roughened portion 25 of the working region 24 only partially around the circumference of the working region. In the illustrative arrangement of FIG. 2, the roughened portion 25 is formed as an arcuate strip 26, and the remainder of the illustrated working region 24 defines a smooth portion 27. With this scheme, the rotation of the spinning chamber 1 (FIG. 1), and thereby the strand 21, in the forward direction will cause the rotating strand to successively engage alternating roughened and smooth portions of the working region 24 in a cyclically intermittent or pulsating pattern. The reverse twist resulting from such pattern maximizes the strength of the strand in the region between the twisting head 12 and the collecting surface 14 while at the same time maintaining stationary the twist point on the collecting surface.

Moreover, since the strand 21 is always in contact with the working region 24 the use of alternating roughened and smooth portions rather than a circumferentially continuous roughened portion, as in the prior art, reduces the drag imparted by the head 12 to the strand 21. This minimizes strand breakage and facilitates start-up of the rotating system.

While in FIGS. 1 and 2 the roughened portion 25 takes the form of a single arcuate strip, such portion may in general take any desired number of possible configurations. For example, in FIG. 3, the roughened portion includes a pair of diametrically opposed arcuate elements 28 and 29 separated by areas of the smooth portion 27.

In FIG. 4, the roughened portion 25 includes a pair of pie-shaped diametrically opposed segments 30 and 31. In FIG. 5, the roughened portion is composed of four symmetrically disposed radial segments 32-35. In FIG. 6, the roughened portion includes a pair of diametrically opposed spherical elements 38 and 39. In FIG. 7, the roughened portion includes three spherical elements 40, 41 and 42 mutually spaced by 120 around the circumference of the working region 24.

It is not necessary, when the roughened portion 25 comprises a plurality of spaced discrete bodies, that such bodies be symetrically disposed in the working region 24, One illustration of an asymmetrical placement of such roughened bodies is shown in FIG. 8, in which a pair of discrete, arcuate roughened elements 36 and 37 are randomly disposed in the working region 24.

The degree to which the strands 21 are strengthened by the arrangements just described is dependent to some degree on the relative sizes of the roughened and smooth portions in the working region. Preferably, the roughened portion should occupy anywhere between 25 and percent of the extent of the working region 24. It has been found desirable that when the roughened portion 25 occupies a lower range in such 25-75 percent spread, the roughened portion should be flush with the smooth portion, as shown in the arrangements of FIGS. 9 and 10. Where, however, the roughened portion 25 occupies a higher range in such spread, the roughened portion should project slightly (e. g. between 0.1 and 0.3 mm) beyond the smooth portion in an axially upstream direction, as illustrated in FIG. 11.

In the case of FIGS. 9 and 10, the roughened portion 25 may be formed as an insert which may be seated in an appropriately shaped recess formed in the smooth portion 27. In one particularly advantageous construction of the working region 24 an annular groove 43 (FIGS. 12 and 13) is cut into the working region for seating the roughened portion 25, which is in the form of a discrete arcuate element 45. The element 45 is seated in a lower arcuate portion of the annular groove.

In a similar arrangement shown in FIG. 14, an edge 54 of the element 45 projects from the groove in an axially upstream direction to provide a localized point of contact with the strand 21 as shown. Such localized contact reduces wear on the roughened portion 25, and is particularly advantageous when strands having high proportions of certain admixtures such as waxy substances, mineral matter or livening agents are employed.

In the arrangement shown in FIG. 15, a second arcuate roughened element 47 may be seated in an upper portion of the groove 43. It will be noted from FIG. 15 that the upstream ends of the roughened arcuate bodies 45 and 46 project from the associated groove 43 by a distance t, thereby establishing a corresponding axial spacing between them and the smooth portion 27 of the working region. I

The roughened portion 25 may be fabricated by any suitable means. For example, where the roughened and smooth portions are integrally formed, arc machining or etching may be appropriate. Where the roughened portion is formed as a separate element to be inserted into the head 12, an appropriate synthetic material such as sintered carbide may be desirable.

In the foregoing, the invention has been described in connection with preferred arrangements thereof. Many variations and modifications will now occur to those skilled in the art. It is accordingly desired that the scope of the appended claims not be limited to the specific disclosure herein contained.

What is claimed is:

1. In a method of advancing strands and twisting them into yarn wherein the strands are advanced through an elongated funnel-shaped twisting head and rotated about the axis of the head in a first circumferential direction to receive a forward twist that results from the continuous engagement of the strands with the interior wall of the head during such rotation the improvement which comprises the step of imparting a cyclically intermittent reverse twist to the rotating strands to strengthen the strands.

2. In an apparatus for simultaneously advancing strands axially downstream and twisting them into yarn, wherein a rotary spinning chamber disposed axially upstream of the advancing means has a collecting surface from which the strand segments are payed out by the advancing means and wherein a twisting head is disposed coaxial with the spinning chamber and positioned between the advancing means and the collecting surface, the twisting head including a funnel-shaped working region including roughened and smooth portions, an improved construction of the working region, in which the roughened portion extends only partially around the circumference of the working region and the smooth portion occupies the remaining portion of the working region, whereby the rotation of the spinning chamber about the axis of advance causes the advancing strands to alternately contact the rough and smooth portions of the working region.

3. A construction as defined in claim 2, in which the roughened portion includes a plurality of mutually spaced discrete roughened elements.

4. A construction as defined in claim 2, in which the roughened portion occupies between 25 and percent of the extend of the working region.

5. A construction as defined in claim 2, in which the roughened portion projects axially in an upstream direction with respect to the smooth portion.

.6. A construction as defined in claim 2, in which the roughened portion and the smooth portion are substantially flush.

7. A construction as defined in claim 2, in which the working region is provided with a circumferential groove, and in which the roughened portion comprises at least one discrete roughened element disposed in the groove.

8. A construction as defined in claim 7, in which the discrete element has an edge projecting axially upstream from the groove for engaging the advancing strands. 

1. In a method of advancing strands and twisting them into yarn wherein the strands are advanced through an elongated funnelshaped twisting head and rotated about the axis of the head in a first circumferential direction to receive a forward twist that results from the continuous engagement of the strands with the interior wall of the head during such rotation the improvement which comprises the step of imparting a cyclically intermittent reverse twist to the rotating strands to strengthen the strands.
 2. In an apparatus for simultaneously advancing strands axially downstream and twisting them into yarn, wherein a rotary spinning chamber disposed axially upstream of the advancing means has a collecting surface from which the strand segments are payed out by the advancing means and wherein a twisting head is disposed coaxial with the spinning chamber and positioned between the advancing means and the collecting surface, the twisting head including a funnel-shaped working region including roughened and smooth portions, an improved construction of the working region, in which the roughened portion extends only partially around the circumference of the working region and the smooth portion occupies the remaining portion of the working region, whereby the rotation of the spinning chamber about the axis of advance causes the advancing strands to alternately contact the rough and smooth portions of the working region.
 3. A construction as defined in claim 2, in which the roughened portion includes a plurality of mutually spaced discrete roughened elements.
 4. A construction as defined in claim 2, in which the roughened portion occupies between 25 and 75 percent of the extend of the working region.
 5. A construction as defined in claim 2, in which the roughened portion projects axially in an upstream direction with respect to the smooth portion.
 6. A construction as defined in claim 2, in which the roughened portion and the smooth portion are substantially flush.
 7. A construction as defined in claim 2, in which the working region is provided with a circumferential groove, and in which the roughened portion comprises at least one discrete roughened element disposed in the groove.
 8. A construction as defined in claim 7, in which the discrete element has an edge projecting axially upstream from the groove for engaging the advancing strands. 